1. Field of the Invention
The present invention relates to a character input device, a mobile terminal, and a character input program for execution of character input on a display screen by use of two or more keys.
2. Description of the Related Art
In a device, such as a mobile phone terminal, in which the number of keys usable for character input is small, generally two or more characters are allocated to one key. In this case, each time the same key is serially pressed (or, the keystroke of the same key is serially entered), a different character is presented serially or one by one as an input candidate on a display screen of the terminal on the basis of selection from among the characters allocated to the key. As such, depending upon the character, the keystroke of the key has to be repeatedly entered to input a character of interest (or, a “target character,” herebelow). In other words, in order to input a single word, a user has to enter a large number of keystrokes relative to the number of characters composing the word. This is a complicated, time-consuming operation for the user.
Various approaches as solutions have been proposed to date against problems such as described above, and some of the solutions are practically used as practical applications.
One of such practical applications is known as a technique called “predicative conversion.” The technique, in the event that either a character under input operation or a character string is entered or input, presents selective items corresponding to the target word predicted in accordance with past input historical log information or context on a display screen to thereby allow a user to make selection. As one of such predicative conversion techniques, “POBox” (Predictive Operation Based On example) is known (“POBox” is a registered trademark of Sony Corporation).
As one of other input techniques, a so-called single-tap technique is known. According to this technique, by serially entering keystrokes of keys to each of which a target character is allocated, a word associated to the keystrokes of the keys and stored in a dictionary is retrieved and presented as a selective item to the user.
Also known is a next word prediction technique in which, in a device, past input history information for predicting a next word desired to be input after a certain word has been input are stored. Thereby, when the certain word is input, a word to be input next (“next word,” herebelow) is predicted in accordance with the input history information, and the predicted word is presented as a selective item to a user.